BackgroundMesenchymal stem cells are multilineage non-hematopoietic progenitor cells that play a key role in supporting the lymphohematopoietic system. Their distribution in bone marrow and secondary lymphoid organs allows an intimate interaction with T-and B-lymphocytes. While their effect on T-lymphocytes has been extensively analyzed, data on the effect of mesenchymal stem cells on B cells are more limited. We analyzed the effects of mesenchymal stem cells on B-lymphocytes and the pathways involved in these effects.

These data suggest that sirolimus has activity in the treatment of steroid-refractory acute GVHD. However, there was considerable toxicity and further dose optimization studies seem warranted.

Summary:Umbilical cord blood (CB) has been rapidly established as an alternative source of stem cells to bone marrow for allogeneic-related and unrelated hematopoietic transplantation. To date, almost 70 000 CB units are available for transplantation and more than 2000 CB transplants (CBT) have been performed, mostly in children, for the treatment of a variety of malignant and nonmalignant conditions. Considerable experience has been rapidly accumulated in this field and many aspects of CBT have been elucidated, while other questions remain unresolved. A concise review of the clinical results achieved after related and unrelated CBT is presented and discussed.